The present invention relates to structures that protect organic optoelectronic devices from the surrounding environment.
Organic optoelectronic devices, including circuits, such as organic light emitting diodes, organic electrochromic displays, organic photovoltaic devices and organic thin film transistors, are known in the art and are becoming increasingly important from an economic standpoint.
As a specific example, organic light emitting devices (xe2x80x9cOLEDsxe2x80x9d), including both polymer and small-molecule OLEDs, are potential candidates for a great variety of virtual- and direct-view type displays, such as lap-top computers, televisions, digital watches, telephones, pagers, cellular telephones, calculators and the like. Unlike inorganic semiconductor light emitting devices, organic light emitting devices are generally simple and relatively easy and inexpensive to fabricate. Also, OLEDs readily lend themselves to applications requiring a wide variety of colors and to applications that concern large-area devices. In general, two-dimensional OLED arrays for imaging applications are known in the art and are typically composed of a plurality of OLEDs (one or more of which forms a pixel) arranged in rows and columns. Each individual OLED in the array is typically constructed with a first transparent anode (such as ITO), an organic electroluminescent layer on the first electrode, and a metallic cathode on the organic electroluminescent medium. Other OLED architectures are also known in the art such as transparent OLEDs (transparent cathode contact), and inverted OLEDs. Substrate materials may include glass, plastic, metal foil, silicon wafers, etc.
In forming an OLED, a layer of metal is typically utilized as the cathode to ensure efficient electron injection and low operating voltages. However, metals and their interface with the organic material are susceptible to oxygen and moisture, which can severely limit the lifetime of the devices. Moreover, moisture and oxygen are also known to increase xe2x80x9cdark spot areasxe2x80x9d in connection with OLEDs. Components of various other organic optoelectronic devices (e.g., organic electrochromic displays, organic photovoltaic devices and organic thin film transistors) are likewise susceptible to attack from exterior environmental species, including water and oxygen.
The above and other challenges are addressed by the present invention.
According to a first embodiment of the invention, a covered substrate is provided, which comprises: (a) a flexible substrate layer; and (b) a plurality of cooperative barrier layers disposed on the substrate layer. The plurality of cooperative barrier layers in this embodiment further comprise one or more planarizing layers and one or more high-density layers. Moreover, at least one high-density layer is disposed over at least one planarizing layer in a manner such that the at least one high-density layer extends to the substrate layer and cooperates with the substrate layer to completely surround the at least one planarizing layer.
According to a second embodiment of the invention an organic optoelectronic device structure is provided, which comprises: (a) a first barrier region comprising a flexible substrate layer and a plurality of cooperative barrier layers disposed on the substrate layer; (b) an organic optoelectronic device disposed over the first barrier region, the organic optoelectronic device selected from an organic light emitting diode, an organic electrochromic display, an organic photovoltaic device and an organic thin film transistor; and (c) a second barrier region disposed over the organic optoelectronic device. As in the prior embodiment, the plurality of cooperative barrier layers further comprises one or more planarizing layers and one or more high-density layers. Moreover, at least one high-density layer is disposed over at least one planarizing layer in a manner such that the at least one high-density layer extends to the substrate layer and cooperates with the substrate layer to completely surround the at least one planarizing layer. Preferred organic optoelectronic devices are organic light emitting diodes.
For each of these embodiments, each overlying first cooperative barrier layer that is disposed over one or more underlying first cooperative barrier layers preferably extends to the substrate layer in a manner such that the one or more underlying first cooperative barrier layers are surrounded by the substrate layer and the overlying first cooperative barrier layer.
Preferably, the first cooperative barrier layers comprise an alternating series of two or more first planarizing layers and two or more first high-density layers, and more preferably comprise an alternating series of 3 to 7 first planarizing layers and 3 to 7 first high-density layers.
The second barrier region in the second embodiment above can, like the first barrier region, comprise a plurality of second cooperative barrier layers, which further comprise one or more second planarizing layers and one or more second high-density layers. At least one second high-density layer is preferably disposed over at least one second planarizing layer in a manner such that the at least one second high-density layer extends to the first barrier region and cooperates with the first barrier region to completely surround the at least one second planarizing layer. The second cooperative barrier layers can be arranged in essentially the same fashion as the first barrier layers.
One advantage of the present invention is that organic optoelectronic structures are produced that provide an effective barrier between the organic optoelectronic device and the ambient atmosphere, reducing adverse effects due to chemical species in the ambient atmosphere, such as moisture and oxygen.
Another advantage of the present invention is that organic optoelectronic structures are provided that address problems associated with lateral diffusion of moisture and oxygen within their barrier layers.
These and other embodiments and advantages of the present invention will become readily apparent to those of ordinary skill in the art upon review of the disclosure to follow.